Mighty Yar got it right, the US had embarked on a massive naval construction program in the early 1920's and was in a position to dictate the terms of the Washington Naval Arms treaty of 1922. If the other nations didn't agree, the US would continue building its fleet. Also helped that the Japanese diplomatic code had been broken, so Japan ended up agreeing to a reduced fleet. One consequence of the treaty was that two of the USN battle cruisers under construction were converted to carriers, and showing the USN that large carriers were more effective than small carriers.
The attack plans on Canada were drawn up as the US experience with WW1 led to vigorous opposition to any thought of engaging in another war in Europe. Opinion polls conducted in 1941 showed about 70% of the US opposed to involvement in Europe, and one result was that The US declared war on Germany on December 11th only after Germany declared war against the US on Dec 10.
The plan to take over the Soviet Embassy to search for nuclear devices wasn't delusional as the Soviets had smuggled in components for a nuclear weapon into the Washington DC embassy.